The present invention relates generally to dental tools for administering filling materials in a tooth. In particular, the present invention relates to a condenser tool for compressing filling materials into a bore of a tooth.
In the dental field, dentists and their assistants are required to fill cavities in decaying teeth. To do so, the dentist first creates a bore in the tooth thereby removing the area of decay. The bore is made larger in the bottom portions of the tooth than the upper portions of the tooth. Next, the bore is filled with a semi-liquid amalgam filling material or a similar metal mixture which later hardens into a solid. The amalgam filling becomes mechanically fixed within the bore because the bore is larger in the bottom portion than in the top so that upon a hardening of the amalgam, the amalgam is anchored within the bore.
Amalgam is a metal mixture typically including mercury and silver, which is prepared and maintained in a semi-liquid state similar to a paste. The amalgam sets into a solid mixture over time in a manner similar to a stone cement. An amalgam carrier tool is used to deliver the amalgam from an amalgam preparation area to mouth of the patient and into the bore in the tooth. The amalgam is then dispensed into the bore in the tooth and pushed down into the bore with a packing or condenser tool to insure that the amalgam has completely filled in the bore of the tooth.
Filling materials other than amalgam can be used to fill in a bore of a tooth. For example, composite filling materials sometimes are used that include either plastic materials or ceramic materials. These composite filling materials are placed within the bore of a tooth and condensed therein with an amalgam condenser tool in a manner similar to that described herein for amalgam filling material.
Conventional tools used for condensing amalgam into a bore have a tip segment that extends outwardly from a body of the tool and that has a surface for contacting the filling material. This contact surface is typically flat and smooth. Alternatively, the contact surface of the condenser tip is flat with a raised crosshatching formed on the contact surface. The dentist uses the contact surface of the condenser tip segment to compress the amalgam filling material into the bore.
Typically the amalgam is installed into the bore in several layers with the dentist using the condenser tool to compress the amalgam into the bore after each layer is installed. The dentist typically compresses the amalgam filling material down into the bore about five times for each layer of amalgam. This ensures that all portions of the amalgam layer have been compressed. A condenser tool with a smaller tip is used for reaching tight spots in the bottom of bore. Afterward, a condenser with a larger tip is used as more amalgam layers are added near the top. The dentist will typically add the layers of amalgam until the bore has been over packed with filling material The dentist then uses a carver tool to remove excess filling material from the top of the tooth. Last, the dentist uses a burnishing tool to shape and polish the top surface of the filling into a smooth contour with the tooth surface.
Several disadvantages plague conventional amalgam condenser tools. As previously discussed, some conventional condenser tools have tips segments with crosshatched contact surfaces for packing the amalgam. Condenser tools with the crosshatched contact surface suffer from a great disadvantage because that surface is susceptible to amalgam building up on the contact surface. The amalgam, once adhered to the crosshatched contact surface, remains thereon even after ultrasonic cleaning and steam autoclaving. Thus, to maintain a clean crosshatched contact surface, the dental practitioner must later clean off the tool with a pick or scraping device.
Moreover, this amalgam build up on the tip of the condenser tool is much more than an inconvenience. The amalgam build up makes it more difficult for the dentist to direct and compress the amalgam filling material in the desired direction. In particular, the amount of compressive force that actually acts on the amalgam decreases because the tip buildup causes the filling material to be pushed off to the side of the tip instead of remaining directly below the contact surface of the tip. To avoid these problems associated with having a condenser tool having a crosshatched tip surface, the dentist may grind off this crosshatching to create a smooth surface tip, or may even discard the tool altogether.
On the crosshatch style of condenser tip where amalgam may occasionally be trapped in the crosshatches even after being sterilized in a steam autoclave, it is theoretically possible that bacteria, viruses or spores may be trapped in between the adherent amalgam and the crosshatch tip. Since an autoclave is designed to sterilize clean, dry items, it may not sterilize a crosshatch style condenser tip that has amalgam trapped on its tip. Since this amalgam was used in a patient's mouth and may occasionally be mixed with saliva or blood, it could contribute to cross-contamination by surviving bacteria, viruses or spores to the next patient or a dental health care worker.
One advantageous feature of having a cross-hatched tip surface is that, after compressing the filling material with this tip surface, a crosshatch impression is formed in the top surface of the amalgam layer at the point at which the tip was pressed. This press point crosshatch impression in the amalgam layer permits the dentist to observe which areas of the amalgam layer have been compressed. This advantageously allows the dentist to ensure that all areas of each amalgam layer are fully compressed before packing the next layer of amalgam into the bore.
However, this advantage of using the cross-hatch tip sometimes vanishes upon regular use of the crosshatch tip condenser tool because of the previously described amalgam build up effect that occurs with regular use of the crosshatched tip tool. The amalgam build up prevents the crosshatch tip surface from forming the crosshatch impression in the amalgam layer surface. Moreover, because the amalgam build up makes the contact surface of the tip irregularly shaped, it becomes even more difficult to identify which areas of the amalgam layer have been compressed. Because of these problems associated with amalgam buildup on the crosshatch tip surface, a dentist often grinds off this crosshatching thereby forfeiting the advantage of locating press points in the amalgam layer by means of the crosshatch impression.
Problems also arise when the crosshatch tip surface is used to condense composite filling materials. When using a crosshatch condenser tip surface to pack composite filling materials, the top layer of filling material tends to adhere to the crosshatch surface. In particular, after pressing the condenser tip contact surface downward onto the filling layer and then withdrawing the contact surface back out of the top layer, the top layer of composite filling material adheres to the crosshatch surface and is pulled outwardly from the bore. Because the lower layers of composite filling material are bound to the top layer of composite material, when the top layer is pulled outwardly from the bore, the lower layers are also pulled out from the bore. As the crosshatch surface effectively tugs a major portion of the entire composite filling back out of the bore, the filling material partially separates from a wall of the bore creating voids in the interface between the bore wall and the filling material. The voids created by the tug back effect are undesirable and should be avoided. Indeed, it is for the precise reason of preventing the formation of voids that such care is taken in sufficiently compressing the filling materials into the bore. Thus, the use of conventional crosshatch tip surface is undesirable when compressing composite filling materials. It is believed that this tug back phenomenon occurs because the composite filling material more easily adhere to the acute angles formed between the raised portions of the crosshatch surface than a smooth contour surface.
Other significant disadvantages are present when using conventional condenser tools to compress filling materials (amalgam or otherwise) into the bore of a tooth. For example, as the dentist uses the condenser tip to apply compressive force to the amalgam, the flat surface of the tip causes the material to squeeze out from under the tip. This squeezing out of the material from under the tip results in attenuating the amount of compressive force applied by the dentist that actually gets transmitted to the amalgam layer. Moreover, recall that the amalgam filling, once hardened, is not adhesively attached within the bore but instead forms a mechanical connection within the bore of tooth. Thus, because the filling material must be mechanically fixed within the bore and because the material tends to squeeze out while being compressed, the dentist must perform many forceful downward pressing motions to ensure that sufficient compressive force has been applied to the amalgam in the bore.
Another, more significant problem associated with the use of conventional condenser tools complicates the application of sufficient compressive force to the amalgam filling. Over several years of administering fillings on a daily basis, the dentist may suffer pain and reduced mobility in the wrist of the hand used to compress the fillings. This pain and reduced mobility in the wrist hampers the dentist's ability to apply sufficient compressive force to the fillings. More importantly, this pain and reduced mobility in the wrist of the dentist is a chronic problem with long term deleterious effects usually associated with carpal tunnel syndrome.
Carpal tunnel syndrome includes the symptoms of debilitating pain and reduced mobility of the wrist caused by long term repetitive flexion bending motions of the wrist, or long term static use of the wrist in a bent flexion position. The carpal tunnel is a semicircular ring of bones in the wrist which defines a passageway for several tendons and nerves to pass from the forearm through the wrist into the hand. The pain and reduced mobility are caused by pressure exerted on the median nerve (extending through the carpal tunnel) by the tendons and bones which compress and rub against the nerve while the wrist is in the bent flexion position.
The particular motion of the dentist's wrist while compressing fillings and examining teeth make the dentist particularly susceptible to suffering from carpal tunnel syndrome. To compress the amalgam filling material into the bore of the tooth, the dentist typically grasps the condenser tool by holding the tip segment of the tool between the index finger, middle finger, and thumb of a hand with the body of the tool extending rearwardly towards and resting on the base of the index finger. Next, while so grasping the tool, the dentist positions the tip of the condenser tool onto the amalgam filling material within the bore of the tooth. The dentist then bends and maintains the wrist into a bent flexion position and then pushes downwardly with the arm to force the tip of the condenser tool into the filling material. Alternatively, the dentist will compress the filling by bending the wrist in flexion to generate the force to compress the amalgam filling material (without using the whole arm to push downwardly). Under either manner of pressing the tip onto the filling material, the dentist must perform a high force bent wrist flexion motion. Because each layer of a filling must be compressed about five times, it is apparent that this high force bent flexion motion of the wrist will be performed many times for each filling and tooth. Moreover, accounting for the number of patients seen daily, it is obvious that this pressing motion is repeated very many times daily. This is the kind of activity that results in carpal tunnel syndrome.
In addition to performing this motion while packing amalgam fillings, the dentist also frequently performs this high force bent wrist flexion motion during a routine dental examination. A dentist can determine that a tooth is decaying if a sharp pointed object is pressed into the tooth surface and the tooth surface tends to retain the tip upon trying to withdraw the sharp tip from the tooth. To perform this test, the dentist presses a sharp tipped elongate tool downwardly (with substantial force) into the tooth surface in the same bent wrist flexion motion previously described for compressing fillings. The dentist must perform this motion several times for each tooth. Thus, during the course of a typical day, the dentist is constantly required to make this high force, bent wrist flexion motion while examining teeth. This stress on the wrist from routine dental examinations compounds the likelihood of the dentist suffering from the long term pain and reduced mobility associated with carpal tunnel syndrome.
Carpal tunnel syndrome is a serious common problem afflicting individuals in work environments in which this high force, bent wrist flexion motion repeatedly occurs. For example, in addition to dentists, workers having the following occupations are susceptible to this syndrome because of the repetitive or continuous stress on the wrists in the bent flexion position: typists, heavy equipment operators, jackhammer operators, cold steel chisel workers, truck drivers, and assembly plant workers. This syndrome results in missed work, workers compensation claims, and lower productivity. Moreover, the pain and reduced mobility hamper the individual's ability to engage in leisure time and household activities, and may ultimately lead to surgery as a treatment option. Thus, this problem found in dentistry is not an isolated instance of occupation specific injury but part of a larger significant problem that has a deleterious effect on workers in many industries.
Several disadvantages are apparent in the conventional condenser tools. First, the conventional condenser tools have flat tip surfaces which tend to cause the filling material to be squeezed out from under the tip surface. This causes a loss of the force applied by the dentist thereby requiring the dentist to exert more effort to apply a sufficient compressive force to the filling. This, in turn, exacerbates the previously discussed stress on the wrist resulting from the dentist's frequent high force, bent wrist flexion pressing motions that cause carpal tunnel syndrome. Second, because of the amalgam build up effect on the crosshatch type tip surface, the tip surfaces do not leave the advantageous press point impressions on the filling surface. Moreover, the amalgam build up problem hinders the dentist's ability to direct the filling material in the desired direction with the minimum amount of force applied. This too compounds the previously described factors which make the dentist susceptible to suffering from carpal tunnel syndrome.
In addition, when the crosshatch tip surface is used to compress composite filling materials, a tug back effect occurs that creates voids between the wall of the bore and the installed layers of filling material. This requires the dentist to make even more bent wrist flexion motions to ensure proper fixation between the bore wall and filling material. Moreover, the disadvantages of using a crosshatched tip surface are further exacerbated when that tip is used with composite filling materials.